LP10 Dry fire trigger weight surprise

[Cobbslane]

Sorry if this is a well known issue but it did surprise a few at the Club today.
I decided to check my Steyr LP10 (mechanical trigger) for trigger weight to ensure it is set as I had believed at beyond the 500g mark. I had done my own measurements as accurately as possible at home but the Club had an approved test weight which I could use.
I set the LP10 up vertical and cocked the trigger and put it into dry fire position. I lifted the weight veerry carefully only to find that the trigger fired before I had lifted the weight. In other words the trigger weight in dry fire was under 500g. I assumed that the trigger weight would need adjustment but was reminded that this is checked with the gun properly cocked and in the true fire position.
I re-cocked it to true fire position and lifted the weight - this time without any issues and had to jerk it slightly to prove the trigger did work - as they apparently are likely to do in the test. This proved - as I had measured myself - that it was set at least 50g over limit.
My qu. is however, that for such a high spec gun surely the trigger weight would be the same for dry fire as true full fire - otherwise some of the benefit of dry firing is lost?

Would be interested in anyone else's experience of this.
Cheers
Gerry

[RobStubbs]

I test mine on dry and it always passes, as it does fully cocked. I don't know if there is much diference though because I've never tested it specifically for that. That said it feels very similar dry firing it as it does live.

Rob.

[Richard H]

Both mine pass on dry and feel close enough that I can't tell the difference (LP10 and LP 10E).

[Tycho]

Sounds like something's fishy in there. Never had an issue like that, in any pistol (and there are some Steyrs among them).

[periodthree]

I had the same problem with a CO2 FWB at the gun check at a recent competition. The trigger pull was less than 500g on dry fire but with a gas cylinder attached and firing with a charge, it passed.

I never thought of it this way, that the trigger behavior is different on dry fire mode. Not happy.

[Cobbslane]

Had a couple of hours this morning to explore this issue a bit further.
The LP10 is about 1 year old and has had about 5000 shots through it. It was lightly used by a previous owner that took good care of it. On purchase I measured the trigger weight (2nd stage) and had it set to 550g but never bothered to check the dry fire position. It was yesterday during a 'club debate' that the testing method arose and the testing of the gun 'dry'. The results are in the itintial post.
Today I checked the settings accurately and found that the test weight properly cocked was now reading 533g (still ok but reduced from original) and in dry fire 524g. I suspect that the club fixed test weight had extra weight applied to ensure a pass when using it by the way.
On looking back at my notes there were a couple of things that I had done that could affect this result - adjusted the trigger stop to a near minimum (which as the manual suggests can create inconsistency in trigger weight) and lowered the trigger blade as well as moving it forward from its 'bought' position.
Firstly, I wasn't happy with the weight now at 533g and so i wound it back up to 550g and rechecked. The trigger weight for both dry and full fire was within 5g at 555g - success! But it got me wondering.....
If you lower the trigger and move it forward you are actually lengthening the 'lever' that is the trigger blade and mechanism. Unless by some engineering trickery Steyr have compensated for this, at a lower position and away from the rear it will take less effort to trigger the gun than if the blade is at its heighest and most rearward point.
I may be wrong on this but for those guys who set their trigger just over the 500g mark such a change could reduce that weight to a failure level of less than 500g.
Or am I talking bol.....
Let me know (as I am sure you will) meanhwhile I will retest much more regularly and after each adjustment.
Gerry

[John Marchant]

That is also my understanding of levers and moments. Lowering the trigger shoe and or moving the trigger forward will reduce the trigger weight as it has increased the moment and leverage. It is always best to recheck the trigger weight after making positional adjustments to the trigger.

[Spencer]

Over the years I have been an EC officer testing trigger weights, and in recent decades a Jury member at EC.

The number of pistols that will not lift the weight on the first attempt but clearly and easily lift the weight for subsequent 'lifts' runs into the thousands!
This across all ISSF calibres, but particularly for Air Pistols.

Perhaps this is an explanation for the original posts observation.

[jipe]

Of course changing the position of the trigger blade changes the trigger weight, it is well known.

But putting the hook of the trigger weight measurement device at a different place on the trigger blade also changes the measured trigger weight.

With clearely curved trigger blades or trigger blades with a groove in the center, the hook of the measurement device always comes at the same place but on other flatter or fully flat trigger blades, it is not the case and then trigger weight measurement becomes a mess and source of lot of discussions.

In my experience. at pistol control (before and after the match), the trigger weight measurement is always done in true fire mode. never in dry-fire mode.

[Spencer]

...In my experience. at pistol control (before and after the match), the trigger weight measurement is always done with in true fire mode. never in dry-fire mode.

8.4.1.6.2 When testing air or gas actuated pistols, the propellant charge should be activated.